1. Field of the Invention
The present invention relates to an integrated suspension, actuator arm and a coil assembly for a magnetic disk drive.
2. Description of Related Art
A disk drive performs recording and reading of signals on a magnetic storage disk. The magnetic disk is rotated by a spindle while a magnetic head contacts the surface of the disk or flies over the surface of the disk on a very thin layer of air (air bearing) created by the high speed movement of the disk. The magnetic head is mounted on a suspension which is pre-loaded to slightly urge the magnetic head against the surface of the disk. This force is balanced by the force of the air bearing to maintain the desired contact pressure or flying height.
In addition to the magnetic head and suspension the drive includes an actuator. The actuator typically employs an actuator arm and a voice coil motor for implementing movements of the suspension and magnetic head. The voice coil motor includes a moving coil and a fixed magnet. In a rotary actuator one end of the actuator arm is mounted to the suspension and the other end of the arm is pivoted and carries the actuator coil. The amount of current applied to the coil determines the movement of the arm and the placement of the magnetic head with respect to the surface of the magnetic disk.
Magnetic heads record either horizontally or vertically, the horizontal recording head being the most prevalent. The horizontal recording head has a pair of pole tips which generate flux in a very thin gap, the fringe flux magnetizing a surface of the disk with desired signals. In the vertical recording head flux is transferred horizontally through the disk between spaced apart pole tips, the horizontally transferred flux magnetizing the disk with desired signals. A major structural difference between horizontal and vertical recording heads is that the horizontal recording head has a precisely defined gap between the pole tips which is typically 2-3 microns thick. Accordingly, the gap must be carefully fabricated by thin film deposition.
U.S. Pat. No. 5,041,932 teaches the fabrication of a perpendicular recording head and suspension which are integrated into a unitary structure. The magnetic head is essentially embedded in one end of the suspension and the other end of the suspension attaches to an actuator arm. Fabrication of the integrated perpendicular recording head and suspension has to be partially completed at the row level. Row level fabrication is necessary in order to lap for throat height and form a vertical portion of a second pole piece of the perpendicular recording head. This process significantly lessens production throughput. The patent does not teach how to fabricate an integrated horizontal recording head and suspension with a precisely defined gap at the recording head surface. The lapping step in the patent cannot be sufficiently controlled to make gaps with thicknesses in the order of 2-3 microns. In addition to constructing the integrated head and suspension the actuator arm and coil have to be constructed. The coil is then assembled to one end of the actuator arm and the suspension is mounted to the other end of the actuator arm. These are labor intensive operations.
There is a strongly felt need to provide integrated magnetic recording head, suspension, actuator arm and actuator coil assemblies which can be fabricated substantially entirely at the wafer level. This would eliminate the labor intensive steps of fabricating separate components and then assembling the components. Further, it is important that the gap of the magnetic head be precisely formed for a longitudinal recording head. There is also a strongly felt need to provide integrated suspension, actuator arm and actuator coil assemblies at the batch level which can be subsequently assembled to a magnetic head and slider.